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The analysis of explosives with ion mobility spectrometry (IMS) directly from aqueous solutions was shown for the first time using an electrospray ionization technique. The IMS was operated in the negative mode at 250 o C and coupled with a quadrupole mass spectrometer to identify the observed IMS peaks. The IMS response characteristics of trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT),...
The use of ion mobility spectrometry systems to detect explosives in high security situations creates a need to determine compounds that interfere and may compromise accurate detection. This is the first study to identify possible interfering air contaminants common in airport settings by IMS. Seventeen suspected contaminants from four major sources were investigated. Due to the ionization selectivity...
Ion mobility spectrometry has become the most successful and widely used technology for the detection of trace levels of nitro-organic explosives on handbags and carry on-luggage in airports throughout the US. The low detection limits are provided by the efficient ionization process, namely, atmospheric pressure chemical ionization (APCI) reactions in negative polarity. An additional level of confidence...
The efficiency of chloride reactant ion formation, when chlorinated hydrocarbon reagent chemicals were added to the ionization region of an ion mobility spectrometer, corresponded to the electron attachment rate constant of the chemical. The chemicals investigated here included chloromethane, dichlormethane, trichloromethane, tetrachloromethane and chlorobenzene, with tetrachloromethane producing...
A novel analysis of explosives via the coupling of an airline passenger personnel portal with a high-flow (HF), high-resolution (HR) ion mobility spectrometry (IMS) was shown for the first time. The HF-HR-IMS utilized a novel ion aperture grid design with a 63 Ni ionization source while operating at ambient pressure in the positive ion mode at 200 o C. The HF-HR-IMS response characteristics...
The results from this study illustrate the first time electrospray ionization-ion mobility spectrometry (ESI-IMS) has been used to separate inorganic cations in aqueous solutions. Using ESI-IMS nine inorganic cation solutions were analyzed. Counter ions affected both the sensitivity and the identity of the response ions. Aluminum sulfate, lanthanum chloride, strontium chloride, uranyl acetate, uranyl...
In this study, the capability of negative corona discharge ion mobility spectrometry (IMS) for quantitative magnitude of several explosives including 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN) and cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) has been evaluated for the first time. The total current obtained with the negative corona discharge was about 100 times larger than...
Ion mobility increment spectrometry (IMIS) is a high sensitive selective ionization technology for detection and identification of ultra-trace constituents, including toxic compounds, CW-agents, drugs and explosives in ambient air or liquid sample. Like an ion mobility spectrometry (IMS), this technology rests on sampling air containing a mixture of trace constituents, its ionization, spatial separation...
The separation efficiency of ion mobility spectrometry (IMS) may be measured in terms of either resolving power, based on a single-peak definition, or peak-to-peak resolution, based on the separation of pairs of adjacent peaks. Usually resolving power decreases with temperature. However, the experimental results show that the peak-to-peak resolution may be increased in some cases. Negative ion mobility...
This paper explains the effect of pressure on separation factor, resolving power (defined based on a single peak), and resolution (defined based on two adjacent peaks) in ion mobility spectrometry. IMS spectra were recorded at various pressures ranging from 39hPa (29Torr) up to atmospheric pressure and various ion gates ranging from 50 to 225μs. The results show that the IMS peaks shift perfectly...
Morphine and noscapine were determined using corona discharge ion mobility spectrometry. The detection limits were 5.6×10 −11 and 6.7×10 −11 g for morphine and noscapine, respectively. The linear dynamic ranges of the calibration plots for the compounds were about three orders of magnitude. The method has also been successfully applied for simultaneous determination of the compounds...
Positive ion mobility spectra of different organophosphorus pesticides such as malathion (s-(1,2-dicarb-ethoxyethyl) o,o-dimethyl dithiophosphate), ethion (o,o,o′,o′-tetraethyl s,s′-methylene bis(phosphorodithioate)) and dichlorovos (2,2-dichlorovinyl dimethyl phosphate) have been studied in air at ambient pressure using ion mobility spectrometry method with 63 Ni ionization source. The limits...
Multiple linear regression and projection pursuit regression were used to develop the linear and nonlinear models for predicting the gas-phase reduced ion mobility constant (K 0 ) of 159 diverse compounds. The six descriptors selected by heuristic method were used as the inputs of the linear and nonlinear models. The linear and nonlinear models gave very satisfactory results; the square of...
The ion mobilities of halogenated aromatics which are of interest in environmental chemistry and process monitoring were characterized with field-deployable ion mobility spectrometers and differential mobility spectrometers. The dependence of mobility of gas-phase ions formed by atmospheric-pressure photoionization (APPI) on the electric field was determined for a number of structural isomers. The...
A system was proposed to remove the upper mass limitation of mass spectrometry. In present study, ultra large molecules were separated in the gas phase by mass analyzer after electrospray ionization. Instead of conventional detection with electron multiplier, a laser-induced-fluorescence detection scheme was applied. The instrument sensitivity is independent of molecular weight, but related to the...
This work demonstrated the potential of using a secondary drift gas of differing polarizability from the primary drift gas for confirmation of a positive response for drugs or explosives by ion mobility spectrometry (IMS). The gas phase mobilities of response ions for selected drugs and explosives were measured in four drift gases. The drift gases chosen for this study were air, nitrogen, carbon dioxide...
This paper describes total determination of aflatoxins B1 and B2 in pistachio samples using corona discharge ion mobility spectrometry (IMS). A new injection port was designed to introduce liquid samples into the IMS. Using this port, the liquid solvent (methanol) containing standard aflatoxins or an extracted sample was directly introduced into the injection port. Calibration curves resulting from...
Characteristic ion mobility spectra for volatile compounds present in fat were used to authenticate the feeding regime of Iberian pigs. Volatile compounds were obtained by heating the solid samples at 150°C for 40min. This produced a headspace that was introduced in the spectrometer ionization chamber by means of a highly purified nitrogen stream. The spectra thus, obtained for the fat samples were...
We present a methodology for fabricating polymer microspheres using inkjet printing of a biodegradable polymer containing either high explosives or high explosive simulant. Poly(dl-lactide/glycolide) 85:15 (PLGA) microsphere production is based on an oil/water emulsion solvent extraction process. The inkjet printing process allows for precise control of the microsphere diameter and the chemical composition...
Ion mobility spectrometry (IMS) is an instrumental technique used successfully for the detection of wide range of organic compounds in the gas phase. In this paper, advances in using special substances called dopants for gases flowing through IMS detectors are reviewed. These substances influence the ion–molecule chemistry in sample ionisation region as well as change conditions for the drift of ions...
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